Bile salts and vitamin B12 (both due to reabsorption problems in terminal ileum)

Most common cause of B12 deficiency

Pernicious anemia

What is the mechanism in pernicious anemia?

Autoimmune destruction of parietal cells and intrinsic factor

What is achlorhydria?

Atrophic gastritis of the body and fundus leading to :

lack of acid which leads to gastric adenocarcinoma

AND

bacterial overgrowth from stasis

Causes for achlorhydria

Tapeworms, pernicious anemia, folate deficiency

Eaten form of folate

Polyglutamate

What converts polyglutamate to monoglutamate?

Intestinal conjugase

What drug blocks intestinal conjugase?

Phenytoin

What is the mechanism of Phenytoin?

Blocks intestinal conjugase

What blocks absorption of monoglutamate from jejunum?

Alcohol and oral contraceptives

What are hypersegmented neutrophils with neurologic deficiency diagnostic for?

Vitamin B12 deficiency

What are hypersegmented neutrophils without neurologic deficiency diagnostic for?

Folate deficiency

What is a characteristic CBC finding in macrocytic anemia?

Pancytopenia

Schilling's test

1. Give radioactive B12 by mouth
2. 24 hour urine collection
3. If nothing comes out, can't reabsorb B12.
4. Then give radioactive B12 and intrinsic factor together by mouth.
5. 24 hour urine collection. If something comes out, it's pernicious anemia. If not, go to step 6.
6. Give broad-spectrum anti-biotic. If you see B12 in the urine, you have bacterial overgrowth. If not, go to step 7.
7. Take pancreatic extract with radioactive B12. If you get B12 in the urine, they have chronic pancreatitis. If not, it could be Crohn's disease, a worm, or some other cause.